Extreme pressure lubricant



July 6, 1965 R. J. HARTLE EXTREME PRESSURE LUBRICANT Original Filed Feb.12, 1959 0 6 6/8 0 E 6F M V w A 0 3 w m 0 6 4 2 0 4 2 0 0 0 0 0 0WQHNNMQ 151/543 4040, x01. oaeAMs IN VENTOR. 05527 J. HARTLE ATTORNEY.

United States Patent 3,193,500 EXTREME PRESSURE LUBRICANT Robert J.l-llartle, Gihsonia, Pan, nssignor to Gulf Research & DevelopmentCompany, Pittsburgh, Pa., a corporation of Delaware Original applicationFeb. 12, 1959, Ser. No. 792,883, new

Patent No. 3,068,259, dated Dec. 11, 1962. Divided and this application.l'une 13, 1962, Ser. No. 202,656

8 Claims. (Cl. 252-32.7)

This application is a division of application Serial No. 792,883, filedFebruary 12, 1959, now US. Patent No. 3,068,259.

This invention relates to certain compounds of molybdenum and tungstenhaving particular utility as additives in lubricating oils and moreparticularly to lubricating oil compositions containing the same.

As is well known to those skilled in the art, uncompounded lubricatingoils frequently fail to provide satisfactory lubrication to surfacesengaging under extreme pressure. The failure of lubricants to provideproper lubrication under high operating pressures results in the rubbingsurfaces of machinery suffering considerable Wear even to such an extentwhere they must be replaced.

This invention is based upon the discovery that certain compounds ofmolybdenum and tungsten which when blended in minor proportions withlubricating oils impart to the resulting composition significantlyimproved extreme pressure characteristics.

The compounds which have been found particularly useful as additionagents in lubricating oils according to the invention are molybdenum andtungsten salts of organic substituted dithiophosphoric acids having thegeneral formula:

RO\ s /P\ :IMX R-O S v in which R is an oil-solubilizing organic radicalsuch as aryl, alkyl, alkoxyalkyl, aralkyl, cycloalkyl, aryloxyalkyl,acylaryl and alkoxyaryl radicals; M is molybdenum or tungsten and X is ahalogen or sulfur, y is the valency of the metal M, z is an integer ofat least one but less than the valency of the metal M and represents thenumber of dithiophosphate ester groups in the product, and v is thevalency of X. More specifically, R in the above general formula isselected from the group consisting of phenyl, caproylphenyl, alkyl,cycloalkyl, alkylphenyl, alkylphenoxyalkyl and alkoxyphenyl radicalswherein said alkyl radical contains 4 to 30 carbon atoms, saidcycloalkyl phatic group are also useful such as for example diphenylradical contains 5 to 6 carbon atoms, the alkyl portion of saidalkylphenyl radical contains 1 to 8 carbon atoms, the alkyl portions ofsaid alkylphenoxyalkyl radical contain 2 to 5 carbon atoms and the alkylportion of said alkoxyphenyl radical contains 2 to 4 carbon atoms. Morespecifically, compounds of this class include a molybdenum or tungstensalt of dialkyl dithiophosphates and dicycloalkyl dithiophosphates suchas dibutyl dithiophosphate, butyl hexyl dithiophosphate, amyl octyldithiophosphate, dihexyl dithiophosphate, di-n-octyl dithiophosphate,diisooctyl dithiophosphate, didecyl dithiophosphate, dilauryldithiophosphate, dihexadecyl dithiophosphate, dioctadecyldithiophosphate, dicyclopentyl dithiophosphate, dicyclohexyldithiophosphate, and so forth. Those dialkyl dithiophosphates in whichthe alkyl group has at least 4 carbon atoms and preferably more than 6carbon atoms as for example from 6 to 30 are preferred since the longeralkyl chains tend to increase the solubility of the dithio phosphates inlubricating oils. The molybdenum and tungsten diaryl dithiophosphatesand the diaryl dithiophosphates in which the aryl group bears an alkylor cycloalidithiophosphate, di-2,4-diamylphenyl dithiophosphate, di-2,4dihexylphenyl dithiophosphate, and the various di-wax substituteddiaryl dithiophosphates. The diaryloxyalkyl dithiophosphates such asdi-2,4-dibutylphenoxyethyl dithiophosphate, di-2,4-diamylphen0xypropyldithiophosphate; the diacylaryl dithiophosphates such as dicaproylphenyldithiophosphate, and the dialkoxyaryl dithiophosphates such asdiethoxyphenyl dithiophosphate, dibutoxyphenyl dithiophosphate and thelike are likewise useful. The organic substituents of the compounds arenot critical and can be selected from a variety of organic radicals onthe basis of their ability to impart oil-solubility to the compounds.

The halogen containing molybdenum and tungsten salts which are utilizedin compositions of the invention are prepared by reacting the desiredmetal halide with an alkali metal salt of a partial ester ofdithiophosphoric acid. Methods of preparing the partial esters ofdithiophosphoric acids and the alkali metal salts thereof are known tothe art. For example, an alkali metal salt of an ester ofdithiophosphoric acid can be prepared by first reacting an appropriatealcohol or hydroxyaromatic compound with phosphorus pentasulfide andthen reacting the partially esterified acid thus formed with sodium orpotassium hydroxide. With regard to the proportions of reactants employed in the preparation of the compounds useful in compositions of theinvention, the amounts of the alkali metal salt of the dithiophosphateester and of the molybdenum or tungsten halide can be variedconsiderably; however, in all cases the mols of dithiophosphate compoundemployed will be less than the number required for reaction with all ofthe halogen atoms. The principal reaction involved in preparing thecompounds useful in compositions of the invention can probably beexpressed by the following illustrative equation, although it isunderstood that it is not desired to be bound by any theory of reaction:

In the above equation, R, M, y and 1 have the meaning indicatedpreviously and X is a halogen.

, Sulfur can be made to replace part or all of the halogen in the abovereaction product simply by causing hydrogen sulfide to react therewithin the presence of a tertiary amine or other acid scavenger.

The synthesis of the oil-soluble molybdenum and tungsten salts useful incompositions of the invention will be better understood from thefollowing illustrative examples.

EXAMPLE I To a solution of 376 grams (1 mol) of sodium diisooctyldithiophosphate in 500 milliliters of carbon tetrachloride is added 84grams (0.31 mol) of molybdenum pentachloride in small portions over atwo hour period. The temperature is maintained at approximately 55 to 60C. during the addition. The reaction mixture is permitted to stand for atime as for example overnight, and the sodium chloride which is formedin the reaction is filtered off. The carbon tetrachloride is distilledoif to leave approximately 390 grams of molybdenum trisdiisooctyldithiophosphate) dichloride. The product is a viscous brown liquid whichturns blue on exposure to air for several hours. It is soluble in thecommon organic solvents.

Analysis.Calculated for Mo: 7.82 percent. for Mo: 7.78 percent.

Found 3 EXAMPLE II EXAMPLE 1H Fifty grams (0.04 mol) of the molybdenumtris-(diisooctyl dithiophosphate) dichloride as prepared in Example I isdissolved in 100 milliliters of benzene containing approximately 0.08mol of pyridine. Hydrogen sulfide is then bubbled slowly through thesolution for about 1 hour. After standing for approximately one hour,the mixture is filtered and the solvent is removed from the filtrateunder reduced pressure. Upon analysis of the final product the sulfurcontent was found to have increased from 13.06 percent to 16.57 percentwhile the chlorine content decreased from'9.70 percent to 3.58 percent.The product is a brown liquid, soluble in common organic solvents.

EXAMPLE IV To a solution of 330 grams (1.0 mol) of sodium dicresyldithiophosphate in 1000 milliliters of carbon tetrachloride is added 84grams (0.31 mol) of molybdenum To a solution'of 432 grams (1.0 mol) ofsodium didecyl dithiophosphate in 1000 milliliters of carbontetrachloride is added 110 grams (0.31 mol) of tungsten pentachloride insmall portions over a two hour period. The temperature is maintained atapproximately 55 to 60 C. during the addition. The reaction mixture ispermitted to stand for atime, as for example overnight, and

the sodium chloride which is formed in the reaction is filtered 0d. Thecarbon tetrachloride is distilled ,oif to leave tungsten tris-(didecyldithiophosphate) dichloride.

EXAMPLE VI To a solution of 528 grams (1.0 mol) of sodium dioctylphenyldithiophosphate in 1000 milliliters of carbon tetrachloride is added 110grams (0.31 mol) of tungsten pentachloride in small portions over a twohour period. The temperature is maintained at approximately to C. duringthe addition. The reaction mixture is permitted to stand for a time andthe sodium chloride which is formed in the reaction is filtered off. Thecarbon tetrachloride is distilled 01f to leave tungstentris-(dioctylphenyl dithiophosphate) dichloride.

EXAMPLE VII 4 EXAMPLE VIII Forty-seven grams (0.04 mol) of molybdenumtris- (dicresyl dithiophosphate) dichloride as prepared in Example IV isdissolved in milliliters of benzene containing approximately 0.08 mol ofpyridine. Hydrogen sulfide is bubbled through the solution untilprecipitation of pyridine hydrochloride is cornplete. After standing forapproximately one hour, the mixture is filtered and the solvent isremoved from the filtrate under reduced pressure to leave molybdenumtris-(dicresyl dithiophosphate) sulfide.

The molybdenum and tungsten organic substituted dithiophosphatesdisclosed hereinabove are particularly useful as additives tolubricating oils to improve the extreme pressure characteristicsthereof. When employed for this purpose, the .additives are employed inlubricating oil compositions preferably in amounts ranging from about0.05 to about 5 percent or more by weight. The exact amount of theadditives to be employed will depend to a great extent upon the purposefor which the oil is intended. For example, an oil intended for use athigh temperatures and high pressures should contain more of the additiveas compared to the amounts required for an oil intended for less severeusage.

The lubricating oil to which the additives are added to form alubricating composition having improved extreme pressure characteristicscan be any mineral oil of lubricating viscosity such as naphthenic base,parafiinic base and mixed base lubricating oils. Synthetic lubricatingoils such as polymerized olefins, organic esters such as di-Z-ethylhexyl sebacate and di-Z-ethylhexyl azelate and the like, can also beused as the base oil to form a lubricating composition in accordancewith the invention. If desired, blends of oils of suitable viscosity maybe employed instead of a single oil.

To prepare an improved lubricating composition in accordance with theinvention the additives disclosed herein can be added to the lubricatingoil base directly or in the form of a mineral oil concentrate in anamount to give the desired concentration in the final lubricatingcomposition. Slight heating of the mixture may be advantageouslyemployed to facilitate blending of the additives in the composition.

To demonstrate the effectiveness of the molybdenum and tungsten salts ofthe type described above in mineral oil compositions contemplated bythis invention, several comparative tests were conducted with a mineraloil alone and with the same oil blended with a commercially availableextreme pressure additive. The mineral :oil employed had the followinginspection:

A four ball wear test was conducted as follows:

Three steel balls are securely fastened so that rotation is impossible.A fourth steel ball in a rotating spindle is placed so that itisentirely supported by the other three balls forming a pyramid. The threeimmobile steel balls and the rotating single steel ball are forced intocontact with each other in response to a vertically applied load.Sufficient test lubricant is poured into a test cup to cover the threelower balls at a predetermined depth. The spindle is revolved at 1800r.p.m. while electrical heating units heat the oil to a temperature of248 F. At the conclusion of the test, wear is measured by examination ofthe scars on the clean surfaces of the three stationaryballs; the twomaximum right angle diameters of each wear scar being measured to theclosest 0.01 millimeter and averaged. The antiwear properties are ratedby the difference in the scar diameters.

Table I Percent Lever load Average Compound added concen- (kilograms)scar tration diameter il lone O 10 0.56 None a 20 0.72

30 1. Z iisooct l dithio hosphate-.. 0.5 20 0.

m0 d y p 0.5 30 0. 40 0. 40 0. 65 0. 5 50 0. 89 1. 0 20 0. 30 1. 0 30 0.35 1. O 40 0.68 a 3-22 Molybdenum tris-(diisooctyl- 0. 5

' te dichloride. 0.5 40 0.63 dithiophospha 0 5 5o 0' 70 1. 0 30 0. 65 10 40 0. 69 528 8'28 re ared in Exam le 0.5 i r ii p r p 0. 5 40 0. 430.5 50 0. 45 1. 0 30 0. 45 1. 0 40 0. 44 1. 0 50 0.48

The results recorded in Table I are shown graphically in the attachedfigure. Thus, curve A shows the results obtained with the oil alone.Curves B and C represent the results obtained with zinc diisooctyldithiophosphate, a commercially available extreme pressure additive atconcentrations of 0.5 and 1.0 percent respectively. Curves D and Erepresent the results obtained with the lubricating oil compositioncontaining molybdenum tris-(diisooctyl dithiophosphate) dichloride atconcentrations of 0.5 and 1.0 percent by Weight respectively. Curves andG represent the results obtained with a lubricating 011 compositioncontaining the reaction product of Example IE1 at concentrations of 0.5and 1.0 percent by Weight respectively.

The curves shown in the figure clearly show the superiority :of thelubricating compositions of this invention particularly in the upperpressure range. It will be seen also from the test results that onlysmall amounts of the additives need be employed to obtain significantimprovement in the extreme pressure characteristics of the lubricatingcomposition.

In addition to the additives disclosed herein, there may be present inthe lubricating composition of this invention other conventionaladditives such as pour point depressants, anti-rust agents,antioxidants, viscosity index improvers and the like.

It is apparent from the foregoing description that the inventionprovides novel lubricating compositions which are eminently satisfactoryfor use as lubricants in applications where high pressures andtemperatures are encountered.

Those modifications and equivalents which fall within the spirit of theinvention and the scope of the appended claims are to be considered partof the invention.

I claim: a;

1. A lubricating composition comprising a major proportion of alubricating oil and a minor amount sufiicient to confer improved extremepressure characteristics to the composition of a compound having theformula:

R-O s X1 R-O S 1 wherein R is selected from the group consisting ofphenyl, caproylphenyl, alkyl, cycloalkyl, alkyphenyl, alkylphenoxyalkyland alkoxyphenyl radicals wherein said alkyl radical contains 4 to 30carbon atoms, said cycloalkyl radical contains 5 to 6 carbon atoms, thealkyl portion of said alkylphenyl radical contains 1 to 8 carbon atoms,the alkyl portions of said alkylphenoxyalkyl radical contain 2 to 5carbon atoms and the alkyl portion of said alkoxyphenyl radical contains2 to 4 carbon atoms; M is a metal selected from the group consisting ofmolybdenum and tungsten; X is an element selected from the groupconsisting of chlorine and sulfur; y is the valency of the metal M; z isan integer of at least one but less than the valency of the metal M; andv is the valency of X.

2. The lubricating composition of claim 1 wherein the said extremepressure improvement additive is present in an amount from about 0.05 toabout 5 percent by weight.

3. A lubricating composition comprising a major proportion of alubricating oil and a minor amount suflicient to confer improved extremepressure characteristics to the composition of a compound having theformula:

iii

wherein R is selected from the group consisting of phenyl,caproylphenyl, alkyl, cycloalkyl, alkylphenyl, alkylphenoxyalkyl andalkoxyphenyl radicals wherein said alkyl radical contains 4 to 30 carbonatoms, said cycloalkyl radical contains 5 to 6 carbon atoms, the alkylportion of said alkylphenyl radical contains 1 to 8 carbon atoms, thealkyl portions of said alkylphenoxyalkyl radical contain 2 to 5 carbonatoms and the alkyl portion of said alkoxyphenyl radical contains 2 to 4carbon atoms; M is molybdenum; X is sulfur; y is the valency ofmolybdenum; z is an integer of at least one but less than the valency ofmolybdenum; and v is the valency of sulfur.

4. A lubricating composition comprising a major proportion of alubricating oil and a minor amount snfiicient to confer improved extremepressure characteristics to the composition of a compound having theformula:

YIZ

wherein R is selected from the group consisting of phenyl,caproylphenyl, alkyl, cycloalkyl, alkylphenyl, alkylphenoxyalkyl andalkoxyphenyl radicals wherein said alkyl radical contains 4 to 30 carbonatoms, said cycloalkyl radical contains 5 to 6 carbon atoms, the alkylportion of said alkylphenyl radical contains 1 to 8 carbon atoms, thealkyl portions of said alkylphenoxyalkyl radical contain 2 to 5 carbonatoms and the alkyl portion of said alkoxyphenyl radical contains 2 to 4carbon atoms; M is tungsten; X is sulfur; y is the valency of tungsten;z is an integer of at least one but less than the valency of tungsten;and v is the valency of sulfur.

5. A lubricating composition comprising a major proportion of alubricating oil and a minor amount suificient to confer improved extremepressure characteristics to the composition of a compound having theformula wherein R is selected from the group consisting of phenyl,

caproylphenyl, alkyl, cycloalkyl, alkylphenyl, alkylphenoxyalkyl andalkoxyphenyl radicals wherein said alkyl radical contains 4 to 30 carbonatoms, said cycloal'kyl radical contains 5 to 6 carbon atoms, the alkylportion of said alkylphenyl radical contains 1 to 8 carbon atoms, theallryl portions of said alkylphenoxyalkyl radical contain 2 to 5 carbonatoms and the alkyl portion of said alkoxyphenyl radical contains 2 to 4carbon atoms; M is molybdenum; X is chlorine; y is the valency ofmolybdenum; z is an integer of at least one but less than the valency ofmolybdenum; and v is the valency of chlorine.

composition of a compound having the formula:

wherein R is selected from the group consisting of phenyl,caproylphenyl, alkyl, cycloalkyl, alkylphenyl, alkylphenoxyalkyl andalkoxyphenyl radicals wherein said alkyl radical contains 4 to 30 carbonatoms, said cycloalkyl radical contains 5 to 6 carbon atoms, the alkylportion of said alkylphenyl radical contains 1 to 8 carbon atoms, thealkyl portions of said alkylphenoxyalkyl radical contain 2 to 5 carbonatoms and the alkyl portion of said alkoxyphenyl radical contains 2 to 4carbon atoms; M is tungsten; X is chlorine; y is the valency oftungsten; z is an integer of at least one but less than the valency oftungsten; and v is the valency of chlorine;

'7. A lubricating composition comprising a major pro- 8 portion of alubricating oil and a minor amount sufficient to confer improved extremepressure characteristics to the composition of molybderiuni'tris-(diisooctyl dithiophosphate) dichloride.

8. A lubricating composition comprising a major proportion of alubricating oil and a minor amount sufiicient to confer improved extremepressure characteristics to the composition of molybdenumtris-(diisooctyl dithiophos-' phate) sulfide. i 7

References Cited by the Examiner UNITED STATES PATENTS 2,346,155 4/44Denison et a1. 25232.7 2,480,673 8/49 Reiff et al. 260429 XR 2,609,3429/52 White et a1. 252-25 3,047,500 7/62 Maston Q 25246.4 3,050,538 '8/62Hugel et al. 252-464 DANIEL E. WY MAN, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR PROPORTION OF ALUBICATING OIL AND A MINOR AMOUNT SUFFICIENT TO CONFER IMPROVED EXTREMEPRESSURE CHARACTERISTICS TO THE COMPOSITION OF A COMPOUND HAVING THEFORMULA: